The ring comes with a cable that connects it frm the 'In' on the ring to the 'Bus' port on your D5 Next.
This port can run up to 90LEDs. Now the ring only has 12 LEDs... but it also has an 'Out' as well, so you can add in another 78 LEDs. That's five more of the standard 15 LED strips, all daisy chained together. Don't forget you can also set up to 20 different controllers in Aquasuite, each with different effects anywhere along that daisy chain.
So, you may not even need the Farbwerk at all - Believe me, I made that mistake, although I'm still going to install mine, just 'because'!
However, if you want to install the Farbwerk as well, that's no problem. Both this and the D5 run their separate channels through Aquasuite and you can configure it however you like!
Flow sensor - The D5 has a virtual one, but if you want a better option, I understand the MPS400 is highly rated -
https://shop.aquacomputer.de/product_inf…roducts_id=2900